Thank you all for wonderful suggestions. As Leigh pointed out , this webpage is wonderful. It is possible to mix powders with below listed liquid chemical
and apply on to plastics and process with heat gun.

This thread could be enlarged in to below thread also , there photo ceramic processes described.

and also this thread connected to

Turn Powder Coating Into a Sprayable Liquid with Liquid-Powder

Powder coating is a popular method of protecting and enhancing the appearance of a part. It is a very "Green" technology and the use of this technology is expanding. However there are some applications where the use of Powder Coating is difficult if not impossible. It has a fair bond to metallic substrates, though the powder is easily damaged prior to baking. Powder Coating of non metallic surfaces is extremely difficult. In addition complex shapes, deep depressions, voids or holes cannot be evenly coated. Generally it is also not possible to multi coat using traditional Powder Coating methods.

This situation has been dramatically changed with the introduction of the Liqui-Powder technology by Tech Line. Now virtually any powder can be mixed in to the Liquid-Powder carrier and sprayed as conventional water based paint. The type of substrate is not an issue, multi coats, special effects, and a host of other custom treatments become available with the use of Liqudi-Powder.

It is even possible to coat substrates that cannot handle the normal cure temperature, but can handle the very low melt temperatures of most powders. Then rather than fully curing, the coating can be protected with a final coat of Cilgen LTC™. Superior chemical and corrosion protection to standard Powder Coated parts is the result.

Mix 48% Liquid-Powder with 52% powder coating by weight. (ie 14.7oz Liquid-Powder to 16oz powder coating). Spray with an HVLP gun or airbrush with a nozzle 2mm or larger, at 60PSI.

One quart of Liquid-Powder will make up approx 1.5 quarts of sprayable liquid.

Liquid-Powder can be used to touch-up areas on a part that has been powder coated (by electrostatic or other method), but has an area that was missed or was damaged in handling:

Repair of a damaged part can be accomplished by using a small touchup brush, toothpick, paperclip, etc… dipped into the Liquid-Powder and lightly applied to the damaged area, allow to dry then bake.
This process can be used to fill small holes in parts as well. If the part has been fully cured a light sanding of the damaged area is recommended to give the repair a surface to hang on to.